Marc Cardinal Ouellet, the former the former archbishop of Quebec, who now heads the Congregation of Bishops, has shot to the top of oddsmakers' lists in the 24 hours since Pope Benedict XVI unexpectedly announced he will retire at the end of the month.

Paddy Power, based in Ireland, lists Ouellet at 7 to 2 odds. Ladbrokes, a London-based betting house, has the Canadian cardinal at 3 to 1 odds.

Ouellet has such "pope-ularity" that he has attracted 65 percent of all wagers at Ladbrokes, spokeswoman Jessica Bridge told ABCNews.com.

Pope Benedict's surprise resignation has only fueled the interest of bettors, said Féilim Mac An Iomaire, spokesman for Paddy Power.

"Last time around [in 2005] we had over 1 million euro betting on the next pope. This time around we certainly expect to exceed that," he said. "We're confident this will be our biggest non-sporting betting event we've ever had."